5. Maintaining Your UPS

Make sure the UPS keeps in contact with its electrical ground at all
times. Don't overload it. If it shows signs of misbehavior or
malfunction, yank it until it's repaired, or replace it.

Your UPS has a battery inside it. Usually it is a lead-acid
type (those are the least expensive for the manufacturer), but both
lithium and gel-cel batteries are sometimes used.

The battery is by far the most vulnerable and failure-prone part
of your UPS. If you have your UPS long enough, you will probably have
battery problems. Once every six months to a year or so you should
recalibrate your UPS's battery sensor, and once every several years
you will have to replace the batteries.

5.1. Service contracts

Some consumer-grade UPSes, and all UPSes designed for serious
data-center use, can be bought with vendor service contracts. These don't
make sense for low-end units that can be replaced cheaply from a local
electronics store. If you're an IT shop with a bunch of UPSes scattered
over a campus, a service contract might make sense, depending on circumstances.
If you have a larger UPS in the 5-10 KVA range, a service contract may be a
valuable hedge against extended downtime.

5.2. Extending battery life

To extend your battery life, (a) avoid deep discharges, and (b)
don't expose them to extremes of heat, cold, or humidity.
Unfortunately there is not much you can do to avoid deep-discharging
your UPS other than living in an area where power outages are few
and short.

5.3. Recalibrating Your UPS

Your UPS's dwell-time calibration will lose accuracy over the life
of the battery. The usual symptom of this problem is that the UPS
overestimates the dwell time it has remaining during outages, but
occasionally it can also lead to an actual bad-battery condition going
undetected and very odd symptoms as a result.

UPSes have a recalibration procedure built into their firmware.
It generally involves deep-discharching and recharging the battery
while the UPS is in a special test mode. Your recipe for triggering
such a recalibration will vary according to your UPS software.

You always need to do this when you install new batteries (see
below). It is a good idea to do it once every six to twelve months
as routine maintenance, but no more often than that; as we noted
previously, deep discharges shorten your battery life.

5.4. Replacing Your Batteries

All modern UPSes have a low-battery alarm and run a periodic
self-test; they will alert you when replacement is needed. Usually
they both flash an indicator and make an alarm sound. If you have a
monitoring daemon set up, they will alert it and you will probably get
warning mail. If you ignore the alarm it will time out, but be
repeated at intervals.

You will occasionally get a false alarm. It's a good idea, if you
get an alarm, to explicitly trigger a UPS self-test the next day and see if
the alarm goes away (the procedure for doing this varies depending on
your UPS software). If the alarm is persistent, you need to replace
the batteries.

It has been reported that bad batteries can also produce symptoms
that mimic inverter failures or wonky control electronics. Even if
your UPS is displaying epileptic symptoms like repeating alarms and
flashing panel lights, a bad battery is the first thing to
suspect.

UPS manufacturers would of course prefer that you replace your
entire UPS when the batteries die, since they make more money that
way. But in fact there is nothing unique or magic about UPS batteries.
They are standard types also used for other applications such as
powering marine electronics, with standard connectors. You can buy
them from sources other than the UPS manufacturer, and sometimes replace
them with equivalents that are better and less expensive.

It's best to wait until the low battery alarm before ordering a
replacement; keeping batteries on the shelf reduces their life unless
you keep them fully charged.

Do not throw old batteries in your regular trash! They contain
toxic metals and acids. Be kind to your environment and hand them to
a qualified party for recycling. Most battery dealers will cheerfully
do this for you. If not, your local garbage company or waste-disposal
authority can explain to you how and where to turn them in
safely.

Many UPS models use gel-cel batteries in standard formats like 12.0
V, 7.2Ah (151x64x94 mm). Warning: Many manufactors sell two or three
different types: standard use, cyclic use and high-current use. UPSes
require high-current and some UPS don't work well with batteries for
standard use, because the voltage goes low too early under high load (the
UPS turns off too fast or the output voltage drops so that the computer
turns off). Standard batteries are for alarm devices, emergency lights or
things like that. For instance Panasonic sells the "LCR127R2PG1"
(standard), and "UPRW1245P1" (high current), Fiamm the "FG20271" (standard)
and "FGH20902" (high current), CSB the "GP1272" (standard) and "HR 1234W"
(high current).

Below, you will find some suggestions for buying replacement
batteries. One important note of caution: at
least one user purchased one of the aftermarket batteries noted below
and found out that they would not fit into his unit. This required
cutting and soldering and other very undesirable things, so be
extremely careful in measuring your batteries — including every
millimeter of the terminal connections, which can cause
problems.

Although you can do a hot swap of your batteries while the
computer is running, it may not be very satisfactory, because the unit
will not know that the batteries have been swapped and your monitor
daemon will continue to show a low-battery indication. To correct
this situation, you must do a discharge and recharge of the
battery. At that point the battery should be calibrated better.

It may take several discharges and recharges of new batteries
before they reach full capacity and the dwell-time calibration is
accurate. If your UPS contains two or more battery units and your
monitoring software reports separate voltage levels for them, one way
to tell is to watch the divergence in voltage levels. As the cells
reach nominal full capacity, their voltages should converge.

5.5. Buying Batteries

APC makes "Replacement Battery Units" for each of the
SmartUPS models, but they sell them directly only in the U.S. Your
local Yamaha SeaDoo shop (if you have one) carries 35 ampere-hour deep
cycle marine batteries that are direct replacements for the kind APC
uses in many of its models. These are gel-cel and will double the
runtime and/or cut your recharge time in half. Here are some West
Coast sources:

The company I've heard most strongly recommended (by Carl
Erhorn, a core developer on the apcupsd
project) is called Battery Wholesale Distributors of Georgetown,
Texas. If you have questions, you can reach them by phone at (800)
365-8444, 9:00AM to 5:00PM (their local time), Monday through
Friday. Carl reports having gotten email from them on the weekends,
although the office is not open then.

The web site, with current pricing, is www.batterywholesale.com.
They will ship outside of the US, they take all the usual credit
cards, and they accept orders by phone or Web.

Carl reports that BWD has found manufacturers who make batteries
in the standard case sizes, but have additional capacity over original
UPS batteries. Often, the difference is as much as 15% or so, and this
can result in additional runtime. It's a nice upgrade for a minor
increase in price.

BWD is also 'green-aware', in that they encourage you to
recycle your old batteries, and will accept the old batteries back
from you if you cannot find a local place that recycles them. You
pay the shipping but other than that, there is no charge.

Carl says "I've been very pleased with their
products, service, and pricing. I hope you find them as helpful to
you as I do. I've been dealing with them since about 1994, and have
never been disappointed. The owner of the place also is very good
on technical issues, so if you have questions on their products, he
can get as technical as you need to go."